Systems and methods for detecting jack contact with ground

ABSTRACT

A system for determining when one or more jacks on a vehicle have contacted the ground may include a pitch sensor that senses a pitch angle of the vehicle and a roll sensor that senses a roll angle of the vehicle. A jack extension system operatively associated with the vehicle jacks extends and retracts the one or more jacks on the vehicle. A control system operatively associated with the pitch sensor, the roll sensor, and the jack extension system monitors the pitch and roll sensors to determine the pitch and roll angles of the vehicle. The control system operates the jack extension system to lower the jacks to the ground and determines that the jacks have contacted the ground based on detected changes in the pitch and roll angles of the vehicle.

TECHNICAL FIELD

This invention relates to vehicles having stabilizing jacks in generaland more specifically to methods and systems for detecting when thestabilizing jacks have contacted the ground.

BACKGROUND

Numerous kinds of vehicles having retractable jacks for stabilizationand/or lifting are known in the art and are used in a wide range ofapplications. Typically, the stabilizing jacks are hydraulicallyoperated and are moveable between retracted and extended positions. Whenin the retracted position, the stabilizing jacks are out of the way andallow the vehicle to move about without interference from the jacks.When in the extended position, the stabilizing jacks contact the groundand support at least a portion, if not the entirety, of the vehicle. Incertain applications, the jacks may be used merely to stabilize thevehicle, whereas in other applications, the jacks my lift all or aportion of the vehicle to level the vehicle or otherwise position thevehicle in a desired attitude.

While such stabilizing jack systems may be manually controlled, manyjack systems are partially- or fully-automated, and use a jackdeployment system to automatically extend or deploy the jacks until theyprovide the desired degree of lift or stabilization. A typical jackdeployment system uses a ground sensing system to first sense or detectwhen the jacks have contacted the ground. Thereafter, the jackdeployment system may use an attitude control system to further extendthe jacks until the vehicle has achieved the desired attitude (e.g.,level or some other attitude).

While the ground sensing systems used by such jack deployment systemsare generally capable of determining when the jacks have contacted theground, they are not without their problems. For example, one type ofground sensing system utilizes a proximity sensor contained within thejack housing. As the jack contacts the ground, a reference elementinside the sensor housing moves. The proximity sensor detects themovement of the reference element and provides a suitable indication tothe jack deployment system that the jack has contacted the ground. Whilesuch proximity sensor systems are generally inexpensive and easy toservice, they are prone to failure as a result of clogging caused bygrease and/or mud build-up in and around the jack housing.

Another type of ground detection system uses pressure sensors ortransducers to detect the hydraulic pressure inside the jack cylinder.When the jack contacts the ground, the hydraulic pressure in thecylinder increases, thereby providing the jack deployment system with anindication that the jack has contacted the ground. While such pressuresensing systems are free of many of the problems associated withproximity sensor systems, they have proven to be no panacea, and alsosuffer from various drawbacks and disadvantages.

For example, most hydraulically operated jack systems utilize one ormore holding valves to hold the jacks at certain positions. The holdingvalves are adjustable and are usually set-up by a maintenance technicianto provide the desired holding characteristics. However, if the holdingvalve pressure is set too high, the ground detection system may providea false indication of ground contact. That is, the pressure required toovercome the jack holding valve may be sufficiently high so as to causethe ground contact system to interpret the high pressure as groundcontact when in fact the jack has yet to contact the ground.

Still another problem is that the back pressure caused by the jackholding valve typically varies depending on the temperature of thehydraulic fluid. When the fluid is cold, the pressure required toovercome the valve will usually increase, again leading to thepossibility of a false ground contact signal. Yet another disadvantageassociated with pressure sensing systems is that the various componentsare relatively expensive and may be difficult to service or may createother maintenance problems.

Besides the reliability and maintenance issues that are associated withthe various kinds of ground detection systems, the failure of the groundsensing system to detect when the jacks have contacted the ground mayresult in other problems, such as an unsafe vehicle attitude or evenvehicle inversion. That is, absent a ground detection signal, the jackdeployment system may continue to extend the jack even though the jackhas already contacted the ground. Unchecked jack extension will almostcertainly result in an unsafe vehicle attitude and may even cause thevehicle to tip or roll over, particularly if the vehicle is on uneven orsloped ground. In other failure modes, a “false positive,” i.e., anindication of jack ground contact when in fact none as occurred, mayprevent the jack deployment system from further extending the jacks,thereby preventing the vehicle from achieving the desired attitude ordegree of stabilization.

SUMMARY OF THE INVENTION

A method for determining when at least one jack on a vehicle hascontacted the ground according to one embodiment of the invention maycomprise the steps of: Sensing at least one of a pitch angle of thevehicle and a roll angle of the vehicle; extending the jack whilemonitoring at least one of the roll angle and the pitch angle of thevehicle; and determining that the jack has contacted the ground when atleast one of the roll angle and the pitch angle has changed by at leasta setpoint value.

A system for determining when one or more jacks on a vehicle havecontacted the ground may include a pitch sensor operatively associatedwith the vehicle so that the pitch sensor senses a pitch angle of thevehicle and a roll sensor operatively associated with the vehicle thatsenses a roll angle of the vehicle. A jack extension system operativelyassociated with the vehicle jacks extends and retracts the one or morejacks on the vehicle. A control system operatively associated with thepitch sensor, the roll sensor, and the jack extension system monitorsthe pitch and roll sensors to determine the pitch and roll angles of thevehicle. The control system operates the jack extension system to lowerthe jacks to the ground and determines that the jacks have contacted theground based on detected changes in the pitch and roll angles of thevehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative and presently preferred exemplary embodiments of theinvention are shown in the drawings in which:

FIG. 1 is a side view in elevation of a drill rig embodying the systemsand methods of the present invention;

FIG. 2 is a drill end view in elevation of the drill rig illustrated inFIG. 1;

FIG. 3 is a block diagram of one embodiment of a system for detectingjack contact with the ground;

FIG. 4 is a flow chart of one embodiment of a method for detecting jackcontact with the ground;

FIG. 5 is a flow chart of a method for determining a resultant pitchvalue and a resultant roll value;

FIG. 6 is a flow chart of a method for operating the non-drill end jacksof the drill rig illustrated in FIG. 1;

FIG. 7 is a flow chart of a method for operating the cab side jack ofthe drill rig; and

FIG. 8 is a flow chart of a method for operating the non-cab side jackof the drill rig.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

One embodiment of a system 10 for detecting jack contact with the groundis shown and described herein as it may be used on a drill rig 12 of thetype commonly used in mining and quarrying operations to drillblastholes (not shown). Alternatively, the system 10 may be used in anyof a wide range of other applications and other vehicle types, as wouldbecome apparent to persons having ordinary skill in the art after havingbecome familiar with the teachings provided herein. Consequently, thepresent invention should not be regarded as limited to the particularvehicle (e.g., drill rig 12) and application (e.g., blasthole drilling)shown and described herein.

Referring now primarily to FIGS. 1-3, drill rig 12 may be provided witha plurality of jacks 14 that may be operated or controlled by a jackextension system 16. In the example embodiment shown and describedherein, jack extension system 16 of drill rig 12 may comprise anautomated or semi-automated jack extension system that may be operatedto automatically extend the various jacks 14 on drill rig 12. In such anembodiment, the system 10 for detecting jack contact with the ground isoperatively associated with the jack extension system 16 and provides tothe jack extension system 16 an indication that the jacks 14 havecontacted the ground or surface 18. After this ground contact indicationhas been provided, the jack extension system 16 may be operated tofurther extend the jacks 14 until the drill rig 12 is level or hasachieved the desired attitude.

More specifically, the system 10 for detecting jack contact with theground may comprise a control system 20 that is operatively associatedwith the jack extension system 16. Control system 20 is also operativelyconnected to a pitch sensor 22 and a roll sensor 24 that are mounted todrill rig 12. Pitch sensor 22 senses a pitch attitude or angle 26(FIG. 1) of drill rig 12 and produces a pitch output signal 28 that isrelated to the pitch angle 26. Similarly, roll sensor 24 senses a rollattitude or angle 30 (FIG. 2) and produces a roll output signal 32 thatis related to the roll angle 30 of drill rig 12.

Referring now primarily to FIG. 4, the system 10 may be programmed orconfigured to implement a method 34 to determine when at least one jack14 has contacted the ground 18. As a first step 35 in method 34, controlsystem 20 determines or senses at least one of an initial pitch angle 26or roll angle 30 of the drill rig 12. The control system 20 willimplement step 35 at the start of the stabilization and/or levelingprocess and in any event before any of the jacks 14 have contacted theground. Generally speaking, control system 20 will sense both theinitial pitch angle 26 and the initial roll angle 30 during step 35,because both initial angles will be needed for the subsequent grounddetection process. However, and as will be described in further detailbelow, the control system 20 need only sense the initial angle (i.e.,the initial pitch angle 26 or the initial roll angle 30) that iscorrelated with the particular jack or jacks 14 that are being extended.That is, in certain situations the control system 20 may not necessarilydetermine or sense both the initial pitch angle 26 and the initial rollangle 30 at step 35.

After the initial pitch and/or roll angles 26 and/or 30 have beendetermined, control system 20 may instruct the jack extension system 16to begin extending the jacks 14 at step 36. Generally speaking, jackextension system 16 will only extend one jack 14 at a time, and system10 will provide a suitable ground contact indication to the jackextension system 16 when each jack 14 has contacted the ground. However,in other embodiments the arrangement may be such that jack controlsystem 16 extends two or more jacks 14 at a time.

For example, in the embodiment shown and described herein, vehicle jacks14 comprise a pair of jacks 38 and 40 mounted to a first or non-drillend 42 of drill rig 12 that are controlled by a single hydraulic valve(not shown). Thus, when operated by jack extension system 16, both thenon-drill end jacks 38 and 40 will extend and retract together. However,another pair of jacks 44 and 46 mounted to a second or drill end 48 ofdrill rig 12 are independently controllable. That is, the jack extensionsystem 16 can extend and retract the drill end jacks 44 and 46independently. In such an embodiment, then, the system 10 will provide aground contact indication when any one of two jacks 14 operatingtogether (e.g., non-drill end jacks 38 and 40) contact the ground 18.For the jacks that are independently controllable (e.g., jacks 44 and46), the system 10 will provide a ground contact indication when eachrespective jack contacts the ground 18.

Regardless of whether the various jacks 14 are independentlycontrollable (e.g., can be extended singly or in pairs), control system20 continues to monitor, at step 50, the pitch and/or roll angles 26and/or 30 as the jack or jacks 14 are being extended. If the pitchand/or roll angles 26 and/or 30 have not exceeded predeterminedsetpoints for the pitch and roll angles 26 and 30, as determined at step52, then control system 20 will continue to extend the jack(s) 14, i.e.,control system will continue to perform steps 36, 50, and 52, asdepicted in FIG. 4. However, once the pitch and/or roll angles 26 and/or30 exceed their respective setpoints, then control system 20 determinesat step 54 that the jack(s) 14 being extended has contacted the ground18. Thereafter, control system 20 may instruct jack extension system 18to terminate jack extension at step 56.

Method 34 may be repeated for each additional jack 14 that is to beextended, except that the initial pitch and roll angles 26 and 30 neednot be sensed (e.g., at step 35) for subsequent jack extensions.

After each jack 14 has been extended until it has contacted the ground18, as determined by the ground contact signals provided to the jackextension system 16 by the control system 20, jack extension system 16may thereafter be operated to further extend the jacks 14 until thedrill rig 12 has been leveled or has otherwise reached the desiredattitude.

A significant advantage of the present invention is that it provides areliable indication of ground contact without the drawbacks anddisadvantages of other types of systems. For example, because thepresent invention does not require the use of proximity sensors in thejack housings, it is free of the reliability and maintenance issuestypically associated with such systems. The present invention is alsofree of the problems and issues typically associated with pressuresensing systems, because it does not rely on the measurement ofhydraulic pressure to determine when the various jacks have contactedthe ground.

Another advantage of the present invention is that the pitch and rollsensors used to sense or measure the pitch and roll angles of thevehicle are typically mechanically robust, highly reliable, andcomparatively inexpensive. Still further, the pitch and roll sensorsutilized in one embodiment are relatively easy to troubleshoot and canusually be tested, in-situ, by the control system 20 to verify properoperation before the jack extension operation begins. Of course, theability to verify the proper operation of the pitch and roll sensors inadvance of the jack extension process should substantially reduce thepossibility of unchecked jack extension resulting from sensor failure.

Still yet another advantage of the present invention is that it can beeasily retro-fitted to existing vehicles having partially- orfully-automated jack extension systems. Indeed, in certain applications,the present invention may be able to use many of the same hardwarecomponents already associated with such systems.

Having briefly described one embodiment of the systems and methods fordetermining jack contact with the ground, as well as some of the moresignificant features and advantages thereof, various exemplaryembodiments of the systems and methods will now be described in detail.However, before proceeding with the detailed description, it should benoted that while the systems and methods are shown and described hereinas they could be implemented on a blasthole drill rig 12 of the typecommonly used in mining and quarrying operations, they could be used onother vehicle types and in other applications, as would become apparentto persons having ordinary skill in the art after having become familiarwith the teachings provided herein. Consequently, the present inventionshould not be regarded as limited to the particular vehicle types,applications, and environments shown and described herein.

Referring back now to FIGS. 1-3, one embodiment of a system 10 fordetecting jack contact with the ground is shown and described herein asit may be used on a blasthole drill rig 12 of the type commonly used inmining and quarrying operations to drill blastholes (not shown).Blasthole drill rig 12 may be comprise a retractable derrick 58 suitablefor supporting a drill string 60 used to drill or form the blastholes.In the embodiment shown and described herein, drill rig 12 is mounted ona pair of crawler tracks 62 that allow the drill rig 12 to be moved or“trammed” from place-to-place to drill the various blastholes. In anembodiment where the drill rig 12 is to be manned, it may also beprovided with an operator cab 64 to allow a drill rig operator (notshown) to monitor and/or operate the various systems and devices ofdrill rig 12.

Of course, drill rig 12 may also be provided with various othercomponents and systems, such as one or more power plants, electricalsystems, hydraulic systems, pneumatic systems, etc. (not shown), thatmay be required or desired for the operation of the drill rig 12.However, because such other components and systems that may comprisedrill rig 12 are well-known in the art, and because a detaileddescription of such other systems and components is not required tounderstand or practice the systems and methods of the present invention,the various other components and systems of drill rig 12 that are notdirectly related to the systems and methods of the present inventionwill not be described in further detail herein.

Drill rig 12 is also provided with a plurality of jacks 14 that may beused to stabilize and/or lift drill rig 12 to the desired attitudebefore the drilling operation begins. In the embodiment shown anddescribed herein, the various jacks 14 are hydraulically powered and arecontrolled by a jack extension system 16. Jack extension system 16extends and retracts the jacks 14 until they make initial contact withthe ground 18 (i.e., as determined by the system and method of thepresent invention). Thereafter, jack extension system 16 may furtherextend the various jacks 14 to level the drill rig 12 or otherwise liftit to the desired attitude.

With reference primarily to FIG. 3, the various jacks 14 of drill rig 12are arranged in pairs. More specifically, a first pair of jacks 38 and40 are mounted to the first or “non-drill end” 42 of drill rig 12,whereas a second pair of jacks 44 and 46 are mounted to the second or“drill end” 48 of drill rig 12. As was briefly described above, the two“non-drill end” jacks 38 and 40 are controlled by a single hydraulicvalve and operate together. That is, when operated by jack extensionsystem 16, both jacks 38 and 40 will extend or retract together. Incontrast, the “drill end” jacks 44, 46 are independently controlled.That is, the jack extension system 16 may extend and retract the drillend jacks 44 and 46 independent of one another. The fact that, in oneembodiment, the non-drill end jacks 38 and 40 cannot be independentlycontrolled is taken into account in the method for operating thenon-drill end jacks 38 and 40, as will be described below.

The jack extension system 16 may comprise any of a wide range of systemsand devices that are now known in the art or that may be developed inthe future that are, or would be, suitable for controlling the variousjacks in the manner described herein and for receiving the groundcontact indication from control system 20. Consequently, the presentinvention should not be regarded as limited to any particular type ofjack extension system 16. However, by way of example, in one embodiment,the jack extension system 16 may comprise a portion of a computerizeddrill control system (not shown) that is operatively connected to thevarious other systems and components associated with drill rig 12,including the hydraulic system that is used to extend and retract thejacks 14.

The control system 20 may comprise a similar type of computer systemthat is configured to communicate with jack extension system 16 providedon drill rig 12. Indeed, and depending on the particular vehicle, thecontrol system 20 may comprise a portion of the computerized controlsystem used to operate the various systems and devices of the vehicle.Alternatively, of course, control system 20 could comprise a separatesystem.

In any event, i.e., regardless of whether control system 20 comprises anindependent system or whether control system 20 comprises a portion ofan existing vehicle control system, control system 20 is programmed toimplement the methods described herein and to interface with theparticular jack extension system 16 on the vehicle. Control system 20also may be configured to interface with any other system or device ofdrill rig 12, as may be required or desired in any particularapplication, as would become apparent to persons having ordinary skillin the art after having become familiar with the teachings providedherein.

Still referring to FIG. 3, control system 20 may also be operativelyconnected to a pitch sensor 22 and a roll sensor 24. Pitch sensor 22 maybe mounted to any convenient location on drill rig 12 so that it sensesor detects the pitch angle 26 of drill rig 12. Pitch sensor 22 producesa pitch output signal 28 that is related to the pitch angle 26 of drillrig 12. See FIG. 1. In one embodiment, pitch sensor 22 senses the pitchangle 26 of drill rig 12 relative to horizontal, which is designated azero pitch angle. Pitch angles 26 toward the non-drill end 42 of drillrig 12 are assigned positive (+) pitch angles, whereas pitch anglestoward the drill end 48 of drill rig are assigned negative (−) pitchangles, as designated in FIG. 1. Alternatively, the opposite signconvention could also be used. The pitch output signal 28 may beprovided in any convenient units, such as degrees or radians.Alternatively, the pitch output signal 28 could be dimensionless. By wayof example, in one embodiment, the pitch output signal 28 is provided tocontrol system 20 in units of degrees.

Pitch sensor 22 may comprise any of a wide variety of pitch sensors thatare now known in the art or that may be developed in the future thatare, or would be, suitable for the intended application. Consequently,the present invention should not be regarded as limited to anyparticular pitch sensor. However, by way of example, in one embodiment,pitch sensor 22 comprises a single axis analog tilt sensor, part no.PN72162000-045, available from Measurement Specialties of Hampton, Va.(US) and sold under the trademark “ACCUSTAR® IP-66 Clinometer.”

Roll sensor 24 may be mounted to any convenient location on drill rig 12so that it senses or detects the roll angle 30 of drill rig 12. In amanner similar to the pitch sensor 22, roll sensor 24 produces a rolloutput signal 32 that is related to the roll angle 30 of drill rig 12,as best seen in FIG. 2. In the embodiment shown and described herein,roll sensor 24 senses the roll angle 30 of drill rig 12 relative tohorizontal, which is designated a zero roll angle. Roll angles 30 towarda non-cab side 41 of drill rig 12 are assigned positive (+) roll angles,whereas roll angles toward a cab side 43 of drill rig 12 are assignednegative (−) roll angles, as depicted in FIG. 2. Of course, the oppositesign convention could also be used. As was the case for the pitch outputsignal 28, the roll output signal 32 may be provided in any convenientunits, such as degrees or radians. Alternatively, the roll output signal32 could be dimensionless. By way of example, in one embodiment, theroll output signal 32 is provided to control system 20 in units ofdegrees.

Roll sensor 24 may comprise any of a wide variety of pitch sensors thatare now known in the art or that may be developed in the future thatare, or would be, suitable for the intended application. Consequently,the present invention should not be regarded as limited to anyparticular roll sensor. However, by way of example, in one embodiment,roll sensor 24 comprises a single axis analog tilt sensor, part no.PN72162000-045, available from Measurement Specialties of Hampton, Va.(US) and sold under the trademark “ACCUSTAR® IP-66 Clinometer.”

Referring now primarily to FIG. 4, the system 10 may implement a method34 for determining when at least one of the jacks 14 provided on drillrig 12 has contacted the ground 18. A first step 35 of method 34involves the determination of the initial pitch angle 26 and/or theinitial roll angle 30 of the vehicle or drill rig 12. In this regard itshould be noted that in most applications, the control system 20 willsense or determine both the initial pitch angle 26 and the initial rollangle 30 of the vehicle (e.g., drill rig 12), because it will be desiredto extend all of the jacks 14, thus affecting both the pitch and rollangles 26 and 30 of the drill rig 12. However, it should be noted thatin certain circumstances it may only be necessary to sense the anglethat is correlated with the particular jacks 14 that are to contact theground. For example, in an embodiment wherein two jacks 14, such asnon-drill end jacks 38 and 40, that are positioned on the same end(e.g., the non-drill end) of drill rig 12 and are also to be extendedtogether, then it may be possible to configure the system 10 so thatcontrol system 20 senses only the initial pitch angle 26, as the pitchangle 26 is strongly correlated with the extension of that pair of jacks14. However, this is a limited application and will not generally beundertaken in most situations.

Once the control system 20 has sensed the initial pitch angle 26 androll angle 30 of drill rig 12, control system 20 may store those initialangles in an appropriate memory system (not shown) for later access andprocessing, as will be described below. The control system 20 may thenexecute step 36 by commanding the jack extension system 16 (FIG. 3) toextend at least one of the jacks 14. Control system 20 will continue tomonitor the pitch and/or roll angles 26 and 30 as the jack 14 isextended. Once the monitored pitch and/or roll angle 26 and/or 30 hasbeen exceeded, as determined at step 52, control system 20 will provideto jack extension system 16 an indication that the jack 14 has contactedthe ground 18. See step 54. Thereafter, control system 20 may instructjack extension system 16 to terminate jack extension at step 56.

Control system 20 may repeat process 34 as necessary for each jack 14that is to be extended, except that the initial pitch and roll angles 26and 30 need only be determined once. After all of the jacks 14 have beenextended so that they are in firm contact with the ground 18, jackcontrol system 16 may further extend the jacks 14 until the drill rig 12has been leveled or has otherwise achieved the desired attitude. In thisregard, jack control system 16 may interface with or utilize an attitudecontrol system (not shown). However, since such subsequent levelingprocesses, as well as systems for performing such leveling processes,are well-known in the art and are not required to understand or practicethe present invention, such leveling processes and systems therefor willnot be described in further detail herein.

As briefly described above, step 52 of process 36 illustrated in FIG. 4involves a determination of whether the monitored pitch and/or rollangles 26 and/or 30 exceed corresponding setpoint values. A method 66for making this determination is illustrated in FIG. 5. A first step 68in the method 66 is to determine the initial pitch value and the initialroll value. These are identical to the initial pitch angle 26 and theinitial roll angle 30 determined in step 35 of method 34. That is, theinitial pitch value is set equal to the initial pitch angle 26, whereasthe initial roll value is set equal to the initial roll angle 30. Instep 70, corresponding pitch and roll setpoint values are determined. Asused herein, a setpoint value is that value that corresponds to theangle change required to ensure that the jack 14 has contacted theground. Thus, the pitch setpoint value corresponds to the pitch anglechange caused by jack contact with the ground 18, whereas the rollsetpoint value corresponds to the roll angle change caused by jackcontact with the ground 18.

The pitch and roll setpoints may be experimentally determined for theparticular vehicle on which the system 10 is to be used. Alternatively,the pitch and roll setpoints may be determined analytically or by someother process. By way of example, in one embodiment, the pitch and rollsetpoints are determined to be 0.1 degree, although other setpointvalues may be used, as would become apparent to persons having ordinaryskill in the art after having become familiar with the teachingsprovided herein. Consequently, the present invention should not beregarded as limited to any particular setpoint value. In addition, thepitch and roll setpoint values need not be identical to one another, butinstead could comprise different values.

The next step 72 in process 66 involves combining (i.e., by addition orsubtraction) the pitch initial value with the pitch setpoint value tocreate a resultant pitch value. Whether the pitch setpoint value isadded to or subtracted from the pitch initial value depends on theparticular sign convention used for the pitch angle 26 and on whetherthe particular jack or jacks 14 that are to be extended will increasethe pitch angle 26 or decrease the pitch angle 26.

For example, and referring back now to FIG. 1, in an embodiment whereinthe pitch angle is deemed to be zero when the drill rig 12 is level oraligned with the horizontal, and positive when the drill rig 12 istilted or pitched toward the non-drill end 42, and wherein the jacks 14being extended are the non-drill end jacks 38 and 40, then the pitchsetpoint value is subtracted from the pitch initial value to create theresultant pitch value. Stated another way, the resultant pitch value isdetermined by subtracting the pitch setpoint value from the pitchinitial value. On the other hand, if either one or both of the drill endjacks 44 and 46 are being extended, then the resultant pitch value isdetermined by adding the pitch setpoint value to the initial pitchvalue.

Step 74 of process 66 involves a similar combination (i.e., by additionor subtraction) of the roll initial value and the roll setpoint value tocreate a resultant roll value. Here again, whether the roll setpointvalue is added to or subtracted from the roll initial value depends onthe particular sign convention used for the roll angle 30 and on whetherthe particular jack or jacks 14 being extended will increase the rollangle 30 or decrease the roll angle 30.

For example, and referring to FIG. 2, in an embodiment wherein the rollangle is deemed to be zero when the drill rig 12 is level (i.e., alignedwith the horizontal), and positive when the drill rig 12 is tilted orrolled toward the non-cab side 41, and wherein the jacks 14 beingextended are the non-cab side jacks 40 and 46, then the roll setpointvalue is subtracted from the roll initial value to create the resultantroll value. That is, the resultant roll value is determined bysubtracting the roll setpoint value from the roll initial value. On theother hand, if either one or both of the cab side jacks 38 and 44 arebeing extended, then the resultant roll value is determined by addingthe roll setpoint value to the initial roll value.

As briefly mentioned above, the particular details of the method 34 usedto detect when the various jacks 14 have contacted the ground 18 mayvary depending on which of the particular jacks 14 are to be extended,whether the jack(s) being extended is a single jack 14 or a pair ofjacks 14, and on the particular sign convention used for the pitch androll angles 26 and 30.

For example, and with reference now primarily to FIG. 6, a process 76for extending the non-drill end jacks 38 and 40 (FIG. 3) may be utilizedwhere both non-drill end jacks 38 and 40 are extended together. That is,process 76 may be used to advantage in systems wherein the non-drill endjacks 38 and 40 are on the same hydraulic circuit and controlled by asingle valve. Accordingly, process 76 may be regarded as a subset orvariation of a portion of the process 34 depicted in FIG. 4, butspecifically configured for determining when the non-drill end jacks 38and 40 (which extend together) have contacted the ground 18. Otherprocesses (e.g., 78 and 80) are specifically configured for the drillend jacks 44 and 46 and will be described in greater detail below.

It should also be noted that process 76 is performed after the controlsystem 20 has sensed the initial pitch and roll angles (e.g., in step35, FIG. 4), and after control system 20 has performed process 66 (FIG.5) to determine the resultant pitch and roll values. In this regard itshould be noted that, because process 76 involves only the monitoring ofthe pitch angle 26, it is possible to carry out process 76 with only thevalues for the initial pitch angle 26, pitch setpoint value, andconsequent resultant pitch value, although in most embodiments, therespective roll values will have been determined as well. In theparticular embodiment shown and described herein, and in accordance withthe teachings provided herein, the resultant pitch value for process 76that involves the extension of the non-drill end jacks 38 and 40 isdetermined by subtracting the pitch setpoint value from the initialpitch value.

Still referring to FIG. 6, control system 20 will begin extending thenon-drill end jacks 38 and 40 at step 36′, e.g., by providing theappropriate commands or instructions to the jack extension system 16. Asmentioned, the non-drill end jacks 38 and 40 will be extended togetherand will generally contact the ground 18 simultaneously. During theextension process, control system 20 will monitor the pitch angle 26,e.g., at step 50′, and compare the monitored pitch angle 26 with theresultant pitch value at step 52′. So long as the monitored pitch angle26 is greater than the resultant pitch value, control system 20 willcontinue to perform steps 36′, 50′, and 52′, as depicted in FIG. 6.

As soon as jacks 38 and 40 contact the ground 18, they will begin toreduce the pitch angle 26 of drill rig 12. That is, drill rig 12 willbegin to pitch toward the drill end 48 of drill rig 12, graduallyreducing the pitch angle 26. As soon as the pitch angle 26 falls belowthe resultant pitch value, as determined in step 52′, control system 20determines, at step 54′, that the non-drill end jacks 38 and 40 havecontacted the ground 18. Thereafter, control system 20 may instruct thejack extension system 16 to terminate the jack extension process at step56′.

A slightly different process 78 may be used to extend the cab side jack44. See FIG. 7. Process 78 differs from process 76 in that the cab sidejack 44 is independently controlled in this particular embodiment andcan be extended without extending any of the other jacks 14 on drill rig12. Process 78 also differs from process 76 in that, once the jack 44contacts the ground 18, further extension of jack 44 will tend toincrease both the pitch angle 26 and the roll angle 30 of drill rig 12.See FIGS. 1 and 2. As was the case for process 76, process 78 is asubset or variation of a portion of the process 34 depicted in FIG. 4,but specifically configured for determining when the cab side jack 44has contacted the ground 18.

Process 78 is also performed after the control system 20 has sensed theinitial pitch and roll angles (e.g., in step 35, FIG. 4), and aftercontrol system 20 has performed process 66 (FIG. 5) to determine theresultant pitch and roll values, as already described. Because process78 involves the extension of the cab side jack 44, the resultant pitchvalue is determined by adding the pitch setpoint value to the initialpitch value. Likewise, the resultant roll value is determined by addingthe roll setpoint value to the initial roll value.

With reference back now to FIG. 7, in step 36″, control system 20 willbegin extending the cab side jack 44 by providing the appropriatecommands to the jack extension system 16. During the extension process,control system 20 will monitor, at step 50″, both the pitch angle 26 andthe roll angle 30 of drill rig 12. Both the pitch angle 26 and rollangle 30 are monitored during the extension process 50″ to ensure thatthe ground detection indication is reliable in the event that both drillend jacks 44 and 46 contact the ground 18 at the same time. That is, inone embodiment, the control system 20 may be programmed or configured toextend both the drill end jacks 44 and 46 at the same time, although onindependent basis. Alternatively, the jacks 44 and 46 could be extendedone at a time.

Control system 20 compares the monitored roll angle 30 with theresultant roll value at step 52″. Control system 20 also compares themonitored pitch angle 26 with the resultant pitch value at step 53″. Solong as neither the monitored roll angle 30 nor the monitored pitchangle 26 exceeds the corresponding resultant value, control system 20will continue to perform steps 36″, 50″ and 52″ and 53″, as depicted inFIG. 7.

As soon cab side jack 44 contacts the ground 18, it will have the effectof increasing the pitch and/or roll angles 26 and/or 30 of drill rig 12.That is, drill rig 12 will begin to pitch toward the non-drill end 42 ofdrill rig 12, gradually increasing the pitch angle 26. See FIG. 1. Inaddition, drill rig 12 may begin to roll toward the non-cab side 41 ofdrill rig, gradually increasing the roll angle 30. See FIG. 2. As soonas either of the monitored roll angle 30 exceeds the resultant rollvalue, as determined in step 52″, or the monitored pitch angle 26exceeds the resultant pitch value, as determined at step 53″, controlsystem 20 determines, e.g., at step 54″, that the cab side jack 44 hascontacted the ground 18. Thereafter, control system 20 may instruct thejack extension system 16 to terminate the jack extension process at step56″.

The present invention may implement yet another process 80 to extend thenon-cab side jack 46. See FIG. 8. Process 80 differs from process 76 inthat the non-cab side jack 46 is also independently controlled in thisparticular embodiment and can be extended without extending any of theother jacks 14 on drill rig 12. Process 80 also differs from processes76 and 78 in that, once the jack 46 contacts the ground 18, furtherextension of jack 46 will tend to increase the pitch angle 26, butdecrease the roll angle 30 of drill rig 12. See also FIGS. 1 and 2.Therefore, and as was the case for processes 76 and 78, process 80 maybe regarded as a subset or variation of a portion of the process 34depicted in FIG. 4, but specifically configured for determining when thenon-cab side jack 46 has contacted the ground 18.

Like processes 76 and 78, process 80 is also performed after the controlsystem 20 has sensed the initial pitch and roll angles (e.g., in step35, FIG. 4), and after control system 20 has performed process 66 (FIG.5) to determine the resultant pitch and roll values. However, becauseprocess 80 involves the extension of the non-cab side jack 46, theresultant pitch value is determined by adding the pitch setpoint valueto the initial pitch value, whereas the resultant roll value isdetermined by subtracting the roll setpoint value from the initial rollvalue.

Referring back to FIG. 8, control system 20 will begin extending thenon-cab side jack 46 in step 36′″ by providing the appropriate commandsto the jack extension system 16. During the extension process, controlsystem 20 will monitor, at step 50′″, both the pitch angle 26 and theroll angle 30 of drill rig 12. Both the pitch angle 26 and roll angle 30are monitored during the extension process 50′″ to ensure that theground detection indication is reliable in the event that both drill endjacks 44 and 46 contact the ground 18 at the same time.

Control system 20 compares the monitored roll angle 30 with theresultant roll value at step 52′″ and compares the monitored pitch angle26 with the resultant pitch value at step 53′″. Control system 20 willcontinue to perform steps 36′″, 50′″, 52′″, and 53′″ for so long as themonitored roll angle 30 is greater than or equal to the resultant rollvalue and the monitored pitch angle 26 remains less than or equal to thecorresponding resultant value. See FIG. 8.

As soon non-cab side jack 46 contacts the ground 18, it will have theeffect of increasing the pitch angle 26, but decreasing the roll angle30. That is, drill rig 12 will begin to pitch toward the non-drill end42 of drill rig 12, gradually increasing the pitch angle 26. See FIG. 1.However, drill rig 12 may begin to roll toward the cab side 43 of drillrig 12, which will gradually decrease the roll angle 30. See FIG. 2.Control system 20 will proceed to step 54′″ if the monitored roll anglefalls below (i.e., becomes less than) the resultant roll value (e.g., atstep 52′″). However, even if the monitored roll angle remains greaterthan or equal to the resultant roll value, control system 20 will stillproceed to step 54′″ if the monitored pitch angle exceeds the resultantpitch value (e.g., at step 53′″). Thereafter, control system 20 mayinstruct the jack extension system 16 to terminate the jack extensionprocess at step 56″.

The present invention may be operated as follows to determine when oneor more of the jacks 14 on drill rig 12 have contacted the ground 18.After the ground contact determination has been made for each of thejacks 14, the jack extension system 16 may be further operated, ifdesired, to further extend the jacks 14 until the drill rig 12 has beenleveled or has otherwise been raised to the desired attitude.

Assuming that the drill rig 12 has been positioned at the desiredlocation, the system 10 may be activated to deploy the various jacks 14until they have made firm ground contact. In one embodiment, thenon-drill end jacks 38 and 40 are deployed first, followed by the cabside jack 44 and the non-cab side jack 46 in that order. Alternatively,other jack deployment sequences may be used. For example, in anotherembodiment, both the drill end jacks 44 and 46 may be deployed atapproximately the same time as the non-drill end jacks 38 and 40 tospeed the process.

With reference now primarily to FIGS. 4 and 5, the control system 20 mayinitiate process 34 by determining the initial pitch and roll angles 26and 30 of drill rig 12. By way of example, and for the purposes ofillustration, assume that the initial pitch angle 26 has been measuredto be +10°, i.e., the drill rig 12 is pitched toward the non-drill end42 by an angle of 10 degrees. Assume also that the initial roll angle 30has been measured to be +15°. That is, the drill rig 12 is rolled towardthe non-cab side 41 by an angle of 15 degrees.

Having determined the initial pitch and roll angles 26 and 30, controlsystem 20 may proceed to process 66 (FIG. 5) to create the resultantpitch values and the resultant roll values. During the first step 68system 20 determines the pitch initial value and the roll initial value.In the embodiment shown and described herein, both the pitch and rollinitial values are set equal to the initial pitch and roll angles 26 and30. Thus, in this particular example, the pitch initial value will beset to +10°, whereas the roll initial value will be set to +15°.

The next step 70 in the process 66 involves the determination of thepitch setpoint value and the roll setpoint value. As described above, inone embodiment the pitch and roll setpoint values are determined inadvance for the specific vehicle (e.g., drill rig 12) and are determinedto be 0.1° each.

Step 72 combines the pitch initial value with the pitch setpoint valueto create a resultant pitch value. As described above, whether the pitchsetpoint value is added to or subtracted from the pitch initial valuedepends on the particular sign convention used for the pitch angle 26,as depicted in FIG. 1, as well as on the particular jack or jacks 14that are to be extended, thus the particular extension process 76, 78,or 80 that will be involved. For example, for the particular signconvention utilized herein for the pitch angle 26, the resultant pitchvalue used for the extension of the non-drill end jacks 38 and 40 (i.e.,involving extension process 76) will be the difference between theinitial pitch value (e.g., +10° in this example) and pitch setpointvalue (0.1° in this example). That is, the resultant pitch valueutilized by extension process 76 will be 9.9°.

In contrast, the resultant pitch value used for the extension of thedrill end jacks 44 and 46 (i.e., involving extension processes 78 and80, respectively), will be the sum of the initial pitch value and thepitch setpoint value. That is, in this example, the resultant pitchvalues used by both processes 78 and 80 will be 10.1°.

Step 74 combines the roll initial value with the roll setpoint value tocreate a resultant pitch value. Here again, whether the roll setpointvalue is added to or subtracted form the roll initial value depends onthe particular sign convention used for the roll angle 30, as shown inFIG. 2, as well as on the particular jack or jacks 14 that are to beextended, thus the particular extension process 78 or 80 that will beused. For example, for the particular sign convention utilized hereinfor the roll angle 30, the resultant roll value used for the extensionof the non-cab side jack 46 (i.e., involving extension process 80) willbe the difference between the initial roll value (e.g., +15° in thisexample) and roll setpoint value (0.1° in this example). That is, theresultant roll value utilized by extension process 80 will be 14.9°.

The resultant roll value used for the extension of the cab side jack 44(i.e., involving extension process 78), will be the sum of the initialroll value and the roll setpoint value. That is, in this example, theresultant roll value used by process 78 will be 15.1°.

In extending the non-drill end jacks 38 and 40, the control system 20will operate in accordance with process 76 illustrated in FIG. 6.Control system 20 may instruct the jack extension system 16 to beginextending the non-drill end jacks 38 and 40. As mentioned, in oneembodiment, both non-drill end jacks 38 and 40 are connected to a singlehydraulic circuit controlled by a single valve, so that they will extendtogether. As the jacks 38 and 40 are being extended, control system 20continues to monitor the pitch angle 26 of drill rig 12 via the pitchsensor 22 (FIG. 3). Control system 20 will continue to extend the jacks38 and 40 until the monitored pitch angle becomes less than theresultant pitch value. In this example, then, the control system 20 willextend the jacks 38 and 40 until the monitored pitch angle becomes lessthan 9.9°. Control system 20 then determines that ground contact hasoccurred (i.e., at step 54′) and may send the appropriate ground contactindication to the jack extension system 16. Thereafter, the extension ofthe jacks 38 and 40 may be terminated at step 56′.

Next, control system 20 may extend the cab side jack 44 by operating inaccordance with process 78 illustrated in FIG. 7. In process 78, controlsystem 20 instructs the jack extension system 16 to begin extending thecab side jack 44 at step 36″. During the extension process, controlsystem 20 will monitor both roll angle 30 and the pitch angle 26 ofdrill rig 12 during step 50″. Control system 20 will continue extendingjack 44 until the monitored roll angle becomes greater than theresultant roll value (step 52″), e.g., until the monitored roll angleexceeds 15.1°, at which point control system 20 will determine that thejack 44 has contacted the ground 18 (i.e., at step 54″). However, evenif the monitored roll angle has not yet exceeded 15.1°, control system20 will nevertheless determine that the jack 44 has contacted the ground18 if the monitored pitch angle exceeds the resultant pitch value (step53″), e.g., 10.1° in this example. Thereafter, the extension of jack 44may be terminated at step 56″.

Control system 20 may extend the non-cab side jack 46 by followingprocess 80 illustrated in FIG. 8. At step 36′″, control system 20instructs the jack extension system 16 to begin extending the non-cabside jack 46. During the extension process, control system 20 willmonitor both roll angle 30 and the pitch angle 26 of drill rig 12 duringstep 50′″. Control system 20 will continue to extend non-cab side jack46 until the monitored roll angle falls below the resultant roll value,e.g., until the monitored roll angle falls below 14.9°, i.e., at step52′″. At this point (i.e., step 54′″), control system 20 determines thatthe non-cab side jack 46 has contacted the ground 18. However, even ifthe monitored roll angle has not yet fallen below 14.9° (i.e., as mightbe determined at step 52′″), control system 20 will neverthelessdetermine that the jack 46 has contacted the ground 18 if the monitoredpitch angle exceeds the resultant pitch value of 10.1° (in thisexample), at step 53′″. Thereafter, the extension of non-cab side jack46 may be terminated at step 56′″.

After having completed these processes, all of the jacks 14 will be infirm contact with the ground 18. Thereafter, jack extension system 18may be further operated if required or desired to further extend thevarious jacks 14 until the drill rig 12 has been elevated to a fullylevel position or has otherwise lifted to the desired attitude.

Having herein set forth preferred embodiments of the present invention,it is anticipated that suitable modifications can be made thereto whichwill nonetheless remain within the scope of the invention. The inventionshall therefore only be construed in accordance with the followingclaims:

1. A method for determining when at least one jack on a vehicle hascontacted the ground, comprising: sensing at least one of a pitch angleof the vehicle and a roll angle of the vehicle; extending the at leastone jack while monitoring at least one of the roll angle and the pitchangle of the vehicle; and determining that the jack has contacted theground when at least one of the roll angle and the pitch angle haschanged by at least a setpoint value.
 2. The method of claim 1, furthercomprising terminating said extending after determining that the jackhas contacted the ground.
 3. The method of claim 1, wherein the vehicleincludes a least a first jack mounted to a first end of the vehicle anda pair of jacks mounted to a second end of the vehicle, and wherein saidextending further comprises: extending the first jack mounted at thefirst end of the vehicle while monitoring the pitch angle of thevehicle; and determining that the first jack has contacted the groundwhen the pitch angle of the vehicle has changed by at least a pitchsetpoint value.
 4. The method of claim 3, further comprising:determining an initial pitch angle before any of the jacks havecontacted the ground; combining the initial pitch angle with the pitchsetpoint value to create a resultant pitch value; and comparing themonitored pitch angle of the vehicle with the resultant pitch value. 5.The method of claim 4, wherein: said combining the initial pitch anglewith the pitch setpoint value comprises subtracting the pitch setpointvalue from the initial pitch angle to create the resultant pitch value;and said determining comprises determining that the first jack hascontacted the ground when the monitored pitch angle is less than theresultant pitch angle.
 6. The method of claim 3, wherein the vehicleincludes a first pair of jacks mounted to the first end of the vehicleand wherein said extending comprises extending the first pair of jackssubstantially simultaneously.
 7. The method of claim 1, wherein thevehicle includes at least a first jack mounted to a first end of thevehicle and a pair of jacks mounted to a second end of the vehicle, andwherein said extending further comprises: extending one of the pair ofjacks mounted to the second end of the vehicle while monitoring thepitch angle of the vehicle and the roll angle of the vehicle; anddetermining that the one of the pair of jacks has contacted the groundwhen one of the following has occurred: the pitch angle of the vehiclehas changed by at least a pitch setpoint value; the roll angle of thevehicle has changed by at least a roll setpoint value; the pitch angleof the vehicle has changed by at least the pitch setpoint value and theroll angle of the vehicle has changed by at least the roll setpointvalue.
 8. The method of claim 7, further comprising: determining aninitial pitch angle and an initial roll angle before any of the jackshave contacted the ground; combining the initial pitch angle with thepitch setpoint value to create a resultant pitch value; combining theinitial roll angle with the roll setpoint value to create a resultantroll value; comparing the monitored pitch angle of the vehicle with theresultant pitch value; and comparing the monitored roll angle of thevehicle with the resultant roll value.
 9. The method of claim 8,wherein: said combining the initial pitch angle with the pitch setpointvalue comprises adding the pitch setpoint value to the initial pitchangle to create the resultant pitch value; said combining the initialroll angle with the roll setpoint value comprises adding the rollsetpoint value to the initial roll angle to create the resultant rollvalue; said determining comprises determining that the one of the pairof jacks has contacted the ground when one of the following hasoccurred: the monitored pitch angle is greater than the resultant pitchangle; the monitored roll angle is greater than the resultant rollangle; the monitored pitch angle is greater than the resultant pitchangle and the monitored roll angle is greater than the resultant rollangle.
 10. The method of claim 8, wherein: said combining the initialpitch angle with the pitch setpoint value comprises adding the pitchsetpoint value to the initial pitch angle to create the resultant pitchvalue; said combining the initial roll angle with the roll setpointvalue comprises subtracting the roll setpoint value from the initialroll angle to create the resultant roll value; said determiningcomprises determining that the one of the pair of jacks has contactedthe ground when one of the following has occurred: the monitored pitchangle is greater than the resultant pitch angle; the monitored rollangle is less than the resultant roll angle; the monitored pitch angleis greater than the resultant pitch angle and the monitored roll angleis less than the resultant roll angle.
 11. The method of claim 7,wherein said extending one of the pair of jacks comprises extending acab-side jack mounted to the second end of the vehicle.
 12. The methodof claim 7, wherein said extending one of the pair of jacks comprisesextending a non-cab-side jack mounted to the second end of the vehicle.13. The method of claim 3, wherein the pitch setpoint value isindependent of the pitch angle of the vehicle and wherein the rollsetpoint value is independent of the roll angle of the vehicle.
 14. Themethod of claim 13, wherein the pitch setpoint value is selected to be0.1 degree and wherein the roll setpoint value is selected to be 0.1degree.
 15. The method of claim 3, wherein the pitch setpoint value isdependent on an initial pitch angle of the vehicle and wherein the rollsetpoint value is dependent on an initial roll angle of the vehicle. 16.A system for determining when one or more jacks on a vehicle havecontacted the ground, comprising: a pitch sensor operatively associatedwith the vehicle, said pitch sensor sensing a pitch angle of thevehicle; a roll sensor operatively associated with the vehicle, saidroll sensor sensing a roll angle of the vehicle; a jack extension systemoperatively associated with the jacks, said jack extension systemextending and retracting the one or more jacks on the vehicle; and acontrol system operatively associated with said pitch sensor, said rollsensor, and said jack extension system, said control system monitoringsaid pitch and roll sensors to determine the pitch and roll angles ofthe vehicle, said control system operating the jack extension system tolower the jacks to the ground, said control system determining that thejacks have contacted the ground based on detected changes in the pitchand roll angles of the vehicle.
 17. The system of claim 16, wherein saidcontrol system senses initial pitch and roll angles of the vehicle andcombines them with respective pitch and roll setpoint values to create aresultant pitch value and a resultant roll value.
 18. The system ofclaim 17, wherein said control system compares monitored pitch and rollangles of the vehicle with the resultant pitch value and the resultantroll value while extending the jacks.
 19. The system of claim 18,wherein said control system determines that the jacks have contacted theground when one of the following has occurred: the monitored pitch angleof the vehicle exceeds the resultant pitch value; the monitored rollangle of the vehicle exceeds the resultant roll value; the monitoredpitch angle of the vehicle exceeds the resultant pitch value and themonitored roll angle of the vehicle exceeds the resultant roll value.